By the time the first English settlers established Jamestown in what would become the Commonwealth of Virginia, slavery was already well-established as a mechanism of providing cheap labor [See the history of slavery in the document linked below]. The institution of slavery in America could be dated to the hundreds of thousands of African slaves brought over by the Spanish, but the first introduction of African slaves brought over by the Dutch and deposited at Jamestown in 1619 is considered the beginning of institutionalized slavery in North America. As the British colonization of North America progressed, the number slaves increased with it until, by the end of the Civil War almost 250 years later, over six million slaves were estimated to have been brought to the shores of the United States.
The British colonials were heavily dependent upon slave labor, especially in the south, where agriculture emerged as the economic mainstay and the rise of the plantation system arose, with its incorporation of slavery as an integral part of the economy and culture. The transatlantic slave trade emerged as a major component of the economy of the British colonies, with the capture, transport and selling of slaves an industry in and of itself. Once transported to North America, the slaves were treated as just another commodity to be bought and sold and were treated as property to be abused at the discretion of the “owners.”
African slaves provided the labor that supported the tobacco and cotton industries that emerged as the most powerful economic components of the southern economy. Tobacco exports to Europe were calculated in relation to the value of the slaves and the institutionalization of slavery in the south was intricately linked to the southern economy such that later 18th Century debates regarding the continued practice of slavery were seen as existential threats in much of the South. The rise of slavery in 17th Century North America, though, all began with that Dutch ship that deposited a couple of dozen kidnapped Africans on the banks of the James River.